"There's nothing that spoils the taste of good ordinary food half so much as the memory of bad magic food" -- what does the "half" mean?

Question

Here is a sentence from The Lion, the Witch and the Wardrobe:

He had eaten his share of the dinner, but he hadn't really enjoyed it because he was thinking all the time about Turkish Delight—and there's nothing that spoils the taste of good ordinary food half so much as the memory of bad magic food.

I don't quite understand what the half adds to the meaning of the whole expression. Is it being used as an intensifier of sorts, and, if paraphrased, could that part of the sentence be something like:

There's nothing at all that spoils the taste of good ordinary food half so much as the memory of bad magic food.

Answer 1

Yes, it's used as an intensifier of sorts - hyperbole, perhaps.

If you turn it around, it claims that regardless what else you might think of that spoils the taste of good ordinary food, the memory of bad magic food is twice as bad.

It doesn't just say that the memory of bad magic food is simply worse - it is saying that it's a lot worse.

The turn of phrase is similar to the following, particularly in its use of a quantifier as a rhetorical device, rather than a strict mathematical comparison:

you don’t know/haven’t heard the half of it used for telling someone that a situation is more shocking or complicated than they think - Macmillan Dictionary